FRS-DAB Converter for Elimination of Circulation Power Flow at Input and Output Ends

Dual active bridge (DAB) converter is the most suitable converter to transfer high power with bidirectional power flow capability and isolation. However, it has the drawbacks of circulation power flow (CPF) and limited range of zero voltage switching (ZVS). To overcome these drawbacks, several modulation strategies have been proposed; however, the CPF can be eliminated either at input or output voltage ends. In order to eliminate the CPF at both input and output sides, a novel front and rear end switch DAB (FRS-DAB) bidirectional dc-dc converter has been proposed in this paper. It has the advantages of lower current stress, extension of ZVS range, higher power transfer capacity, and improved efficiency compared to the conventional DAB converter. The paper presents the detailed operating modes and analysis of power flow control for the proposed FRS-DAB converter. The operation and analytical results of the proposed converter have been verified through the experimental results using an FPGA Spartan 3AN processor.